The bar-lock is a type of lock known for thousands of years. This type of lock was in use in ancient walled cities, in which a large brace, typically a piece of timber wood, or an entire tree trunk, was placed against the width of a gate from the inside, the gate normally opening inward as shown in prior art FIG. 1A. In later prior art, a metal bar was placed in U-shaped or L-shaped anchor braces fastened to each side of the gate posts to hold the bar firmly against the gate, thus preventing the gate from opening, as shown in prior art FIG. 1B. With advances in technological developments, the locking function of the bar-lock was limited to locking stables, barns, sheds, and the like, where the brace locks the doors from the outside and prevents the exit of livestock from secure areas. Additional prior art designs of bar type locks are shown in FIGS. 2-5.
A modern example of the prior art use of bar-locks is described in U.S. Pat. No. 4,548,058 to the present inventor, in which protected hasps are mounted alongside the opening of, for example, a double-door (see FIG. 6) so as to mesh when the doors are closed, with a padlock body being inserted within one opening in the hasps to join with a shackle inserted into an opposing opening in the hasps and locked in place with a key. This is known as a protected hasp lock.
Protected hasp locks, such as that described, are inconvenient to use. This is because once the padlock is opened, the padlock body and shackle must be stored until the lock is re-closed, and they may be misplaced and difficult to find. In addition, it is inconvenient and sometimes difficult for a user to operate the prior art padlock with only one hand free, since it needs both hands in order hold the lock body at the same time as using a key.
Therefore, it would be desirable to provide a lock having the advantageous security features of the protected hasp lock, and the simplicity of a bar-lock.